The aim of this study was to assess the spatial and ontogenetic changes in diet of the flatfishes Citharichthys spilopterus Günther, 1862 and Symphurus tessellatus (Quoy & Gaimard, 1824) in the Sepetiba Bay. The studied area was divided in three zones (inner, central e outer), where bottom trawls were performed during the day, from October 1998 to September 1999. Citharichthys spilopterus showed higher Indices of Relative Importance (IRI) for Mysidacea (0.3359) and Amphipoda (0.0805), while S. tessellatus showed the highest IRI for Amphipoda (0.7515) and Polychaeta (0.2586). The high percentage (67.61%) of empty guts in S. tessellatus suggests nocturnal feeding activity. Smaller sized individuals (TL < 115 mm) of C. spilopterus fed on Mysidacea in the three bay zones, while the larger sized (TL > 115 mm) fed on Polychaeta the inner zone, Gobiidae in the central and Decapoda in the outer. The smaller individuals (TL < 155 mm) of S. tessellatus fed mainly on Amphipoda while the largest (TL > 155 mm) fed on Polychaeta in the inner zone, and Amphipoda and Polychaeta in the outer zone. Citharichthys spilopterus, shows comparatively larger mouth and eye, and feed on organisms in the water column nearby, with a more specialized feeding habit, compared with S. tessellatus, which feed on organism on the substrate. Although the two species feed basically on Crustacea, they present low overlaping in the diet (0.197), and this is probably the trophic strategy developed to allow the coexistence of these two closely related species in the Bay.
Bays; demersal fishes; diet; feeding habits
